db2 union

You can merge with union or union all when two or more separate queries need to be merged together.The union will return all rows that have been stripped of duplicates, and union all will return all rows. At the same time, the union all consumes less resources than

Several well-known result set operation commands have been tested in detail today, and some problems have been found. Suppose we have a table student, which includes the following fields and data: drop table student;create table student(id int primary key,name nvarchar2(50) not null,score number not null);insert into student values(1,'Aaron',78);insert into student values(2,'Bill',76);insert into student values(3,'Cindy',89);insert into student values(4,'Damon',90);insert into student values(5,'

SQL Union operator The Union operator is used to merge the result sets of two or more select statements. Note that the SELECT statement inside the Union must haveSame quantity. Columns must also haveSimilar data types. In additionSequenceMust be the same. SQL Union syntaxSelect column_name (s) from table_name1Uni

Set OperationsSet Operators---- MergeUnion/Union all ---- IntersectionIntersect ----Minus Set Operation Specifications-The select list of the Two Queries must match the number of queries.-The data type of each column in the second query must match the data type of the corresponding column in the first query.-Brackets can be used to change the execution sequence.-Order by can or can only appear at the end of the entire statement. Except

SQL Union operator The Union operator is used to merge the result sets of two or more select statements. Note: The SELECT statement within Union must have the same number of columns. Columns must also have similar data types. In addition, the columns in each select statement must be in the same order. The column name in the

I. Joint result set1. Simple result set Union:Select Fnumber,fname,fage from T_employee Union select Fidcardnumber,fname,fage from T_employee2. Basic principle: Each result set must have the same number of columns: the columns of each result set must be type-compatible.3. Select Fnumber,fname,fdepartment from T_employee Union select Fidcardnumber,fname,fage, ' temp, no department ' from T_employeeSecond,

One Limit of UNION is that the columns generated by two SQL statements must be of the same data type. In addition, when we use the UNION command, we only see different data values (similar to select distinct ). Union only Concatenates the two results and displays them together. It does not join two tables.The syntax of UNION